... step between tryptophan and the important brain chemical serotonin.What are 5-HTP and Sleep Support with 5-HTP?5- ... is the immediate precursor of serotonin. Low levels of serotonin are associated with sleep problems, depression, anxiety, compulsive disorders (including ... migraines, fibromyalgia, and low pain threshold. Many people that are afflicted with one of these conditions often have others, which ...